The following MSKB article may help:
XL: "Cannot Shift Objects Off Sheet" Error Hiding Columns
http://support.microsoft.com/default.aspx?id=211769
Also, Dave Peterson posted this advice:
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Someone with the same problem posted back that their comments were
getting resized causing the trouble.
Maybe enabling: Tools|Options|View|Comment and indicator
(at least for a little bit will help.)
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Or, perhaps William's suggestion in the following posting will help:
http://groups.google.com/groups?hl=en&selm=#SyiwlGICHA.2580@tkmsftngp09
He advised the following:
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"if you have a button on your worksheet, right click on the button,
select "Format Control", select "Properties" and then select "Move and
Size with cells"
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